1. Field of the Invention
The present invention relates to a shift controller, particularly relates to a shift controller of a transmission provided with a twin clutch the engagement/the disengagement of which is controlled by the supply of oil pressure.
2. Description of Background Art
Heretofore, a twin clutch type transmission which is provided with a pair of clutches (a first clutch, a second clutch) between a crankshaft and a main shaft of the transmission and which enables a sequential shift without interrupting the transmission of the driving force of an engine by controlling the alternate engagement/the disengagement of the first clutch and the second clutch in parallel with operation for a shift by an actuator is known.
In JP-A No. 2007-92907, a twin clutch type transmission that controls the engagement/disengagement of two clutches by a single linear solenoid valve that controls supply oil pressure from an oil pressure supply source and a shift valve that switches a destination of supply oil pressure to either of the first or the second clutch is disclosed.
In the twin clutch type transmission disclosed in the JP-A No. 2007-92907, it is conceivable that the engagement of both a dog clutch for first speed and a dog clutch for second speed is set in switching from a neutral condition to a state in which gears are engaged so as to enable the execution of a shift between the first speed and the second speed by only control over the engagement/disengagement of the clutches. However, when the simultaneous engagement of a pair of dog clutches is tried according to the turning of a shift drum, a situation in which a dog tooth (a dowel) is not smoothly fitted into a dog slit (a slit) is apt to occur. At this time, when the two clutches are disengaged and the rotation of a main shaft is stopped, measures such as pressing and dragging a vehicle and turning a countershaft of the transmission are required so as to release the situation.
In addition, as disclosed in JP-A No. 2007-92907 JP-A No. 2007-92907, a shift from a state in which predetermined speed is established is executed by switching a destination of supply oil pressure from engaged one clutch to the other disengaged clutch. At this time, in control that the destination of supply oil pressure is only switched with maximum oil pressure applied, a shift shock may be increased. For a method for coping with this situation, it is conceivable that after oil pressure applied to one clutch is once removed, a destination of supply oil pressure is switched and the supply to the other clutch is started, however, this method has a problem that it is apt to take much time to shift.